xcode-select : error : tool 'xcodebuild' requires Xcode - new error with nativeaot in .NET 9 preview 2

[LLT21]

With the following project file settings:

    <TargetFramework>net9.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <PublishAot>true</PublishAot>
    <RuntimeIdentifier>osx-arm64</RuntimeIdentifier>

when publishing in release mode, I receive the following errors on my Mac M1 with .NET 9 preview 2, which I do not have with previous versions:

Restore complete (0,3s)
You are using a preview version of .NET. See: https://aka.ms/dotnet-support-policy
  lib2 failed with errors (0,3s) → bin/release/net9.0/osx-arm64/lib2.dll
    xcode-select : error : tool 'xcodebuild' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance [/Users/llt/Projects/dotnetoni/libs/lib2/lib2.csproj]
    /Users/llt/.nuget/packages/microsoft.dotnet.ilcompiler/9.0.0-preview.2.24128.5/build/Microsoft.NETCore.Native.Unix.targets(243,24): error MSB4086: A numeric comparison was attempted on "$(_XcodeVersion)" that evaluates to "" instead of a number, in condition "'$(_XcodeVersion)' >= '15'". [/Users/llt/Projects/dotnetoni/libs/lib2/lib2.csproj]

Build failed with errors in 0,8s

[dotnet-policy-service]

Tagging subscribers to this area: @agocke, @MichalStrehovsky, @jkotas
See info in area-owners.md if you want to be subscribed.

[jkotas]

@LLT21 Please check https://stackoverflow.com/questions/55939354/tool-xcodebuild-requires-xcode-but-active-developer-directory-library-devel for how to work around this issue for now.

This is regression from #97856 / #98726 . cc @VSadov @filipnavara

Can we check e.g. clang --version to avoid depending on command-line tools being configured for XCode?

[filipnavara]

I'm not sure if the same regex works for the build version of other tools.

For reference, on my machine:

> xcodebuild -version
Xcode 15.2
Build version 15C500b
> clang --version
Apple clang version 15.0.0 (clang-1500.1.0.2.5)
Target: arm64-apple-darwin23.3.0
Thread model: posix
InstalledDir: /Applications/Xcode-15.2.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
> ld -v      
@(#)PROGRAM:ld  PROJECT:dyld-1022.1
BUILD 05:27:37 Dec  7 2023
configured to support archs: armv6 armv7 armv7s arm64 arm64e arm64_32 i386 x86_64 x86_64h
will use ld-classic for: armv6 armv7 armv7s arm64_32 i386 armv6m armv7k armv7m armv7em
LTO support using: LLVM version 15.0.0 (static support for 29, runtime is 29)
TAPI support using: Apple TAPI version 15.0.0 (tapi-1500.0.12.8)
Library search paths:
Framework search paths:
> xcrun --show-sdk-version
14.2
> xcrun --show-sdk-build-version
23C53
> xcrun --show-sdk-platform-version
14.2

The clang version only loosely correlates to the Xcode version, so it's not perfect. We'd lose the ability to enable the new ld64 on minor Xcode release, at very least.

Xamarin also has a similar check, so we should double check what they are doing.

[filipnavara]

Xamarin also has a similar check, so we should double check what they are doing.

https://github.com/xamarin/xamarin-macios/blob/a150c6068c1b5659af4f0b7217bdf572c1e213b4/dotnet/targets/Xamarin.Shared.Sdk.targets#L1599-L1601
https://github.com/xamarin/xamarin-macios/blob/a150c6068c1b5659af4f0b7217bdf572c1e213b4/msbuild/Xamarin.MacDev.Tasks/Tasks/DetectSdkLocationCore.cs#L210
I don't see where AppleSdkSettings is coming from... (and not at my computer at the moment to do proper search)
...and AppleSdkSettings here, which gets too complicated:
https://github.com/xamarin/Xamarin.MacDev/blob/main/Xamarin.MacDev/AppleSdkSettings.cs

[filipnavara]

For reference, on the same machine with just command line tools installed:

> xcodebuild -version
xcode-select: error: tool 'xcodebuild' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance
> clang --version
Apple clang version 15.0.0 (clang-1500.1.0.2.5)
Target: arm64-apple-darwin23.3.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
> ld -v  
@(#)PROGRAM:ld  PROJECT:dyld-1022.1
BUILD 13:21:42 Nov 10 2023
configured to support archs: armv6 armv7 armv7s arm64 arm64e arm64_32 i386 x86_64 x86_64h
will use ld-classic for: armv6 armv7 armv7s arm64_32 i386 armv6m armv7k armv7m armv7em
LTO support using: LLVM version 15.0.0 (static support for 29, runtime is 29)
TAPI support using: Apple TAPI version 15.0.0 (tapi-1500.0.12.8)
Library search paths:
Framework search paths:
> xcrun --show-sdk-version
14.2
> xcrun --show-sdk-build-version
23C53
> xcrun --show-sdk-platform-version
14.2
> pkgutil --pkg-info=com.apple.pkg.CLTools_Executables
package-id: com.apple.pkg.CLTools_Executables
version: 15.1.0.0.1.1700200546
volume: /
location: /
install-time: 1707554069

[jkotas]

the same regex works for the build version of other tools.

The regex picks up the first number that it sees in the output. As far as I can tell, it works for the clang output just fine.

We'd lose the ability to enable the new ld64 on minor Xcode release, at very least.

We just need something simple that works out-of-the-box for the common cases. The logic does not need to be perfect. In case we need to do something extra for minor xcode releases in future, we can deal with once it shows up.

[LLT21]

For your information: on my MacBook Air M1 I do not have Xcode installed, only the command line tools. This because it only has 256GB and Xcode is pretty big. Up to now this worked fine up to .NET 9 preview 1 for NativeAOT compilation of asp.net applications.